51. Where is North channel? 52. What waters does it connect? 53. What
countries does it separate?
54. _What is a Frith?_ 55. Where is the Frith of Clyde? 56. What friths
in the northern part of Scotland? 57. What in the eastern?
58. What rivers in the southern part? 59. What rivers between Murray
Frith and Frith of Tay?